R32
Also known as: R-32, HFC-32, difluoromethane
Short definitionThe gas of today’s split air conditioners and heat pumps; a single-component HFC. Its GWP is 675 and its class is A2L, which means it is flammable, if only mildly.
A cold room contractor sees R32 not in a cylinder but inside the blend in use: it makes up roughly a quarter of R449A and a fifth of R454C, and it is what gives the blend its capacity. On its own it is a gas for air conditioning, heat pumps and chillers. Being a pure substance, it has no glide. Its boiling point is −52 °C. Compared with R410A its greenhouse effect is one third, and the charge needed is 20–30% smaller.
Its pressure is slightly above that of R410A; so it is not charged into an R410A unit, and every part from the compressor to the fittings must be approved for R32. Discharge temperature runs 10–20 K higher, and at low evaporating temperatures a compressor with injection is required. Because it is flammable, EN 378 limits the charge according to room volume and mounting height. Service uses A2L-approved equipment that produces no sparks, the area is ventilated, and the circuit is purged with nitrogen before brazing.